RFR 8222379: JFR TestClassLoadEvent.java failed due to EXCEPTION_ACCESS_VIOLATION

[coleen.phillimore at oracle.com]

Summary: Give fatal error if CDS loses archive mapping; but map Windows 
RW because remapping is dangerous.

Ioi and I discussed this change and thought it is best.  Windows only 
maps the CDS archive around 50% time because of ASLR and this retains 
the startup performance improvements for CDS on windows.

Tested with mach5 tier1-3.

open webrev at http://cr.openjdk.java.net/~coleenp/2019/8222379.01/webrev
bug link https://bugs.openjdk.java.net/browse/JDK-8222379

Thanks,
Coleen